Goodwill and Other Intangible Assets - Other Intangible Rollforward (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018
Finite-lived Intangible Assets [Roll Forward]
Other intangible assets balance at December 31, 2017		$ 10,269
Acquisitions		136
Foreign currency translation		(22)
Amortization of other intangible assets		142
Other activity, net		(18)
Other intangible assets balance at June 30, 2018	$ 10,223	$ 10,223
Amortization of other intangible assets	$ 4